超大直径土压平衡盾构穿越高水压砂性地层土体改良技术研究

Study on Soil Improvement Technology of Super-large Diameter Earth Pressure Balance Shield Tunneling Through High Water Pressure Sandy Strata

超大直径土压平衡盾构全断面穿越砂性地层时,会面临盾构推力及扭矩增大、土仓压力及螺旋机压力不稳、螺旋机喷涌导致开挖面失稳等风险,需要对开挖面土体进行改良。选取泡沫剂作为土体改良材料,通过试验揭示了泡沫剂不同发泡浓度、发泡率与泡沫寿命的关系,并且测定了改良后土体的物理及力学特性,建立了基于发泡材料的改良土体控制方法,形成了高风险开挖面土体改良技术,有效降低了高水压砂性地层盾构穿越施工风险,为同类型施工提供了技术参考。

When the super-large diameter earth pressure balance shield passes through the sandy stratum,it faces risks such as increased shield thrust and torque,unstable soil chamber and screw conveyor pressure,and excavation face instability due to screw conveyor blowouts.Therefore,the soil at the excavation face needs to be improved.Foaming agents are selected as materials for soil improvement.The relationship between different foaming concentrations,foaming rates,and foam lifespan of the foaming agents is revealed through experiments.Moreover,the physical and mechanical properties of the improved soil are measured,and a control method for the improved soil based on foaming materials is established.Ultimately,a high-risk excavation face soil improvement technique is formed,which effectively reduces the construction risk of shield crossing in high water pressure sandy strata,and provides technical reference for the same type of construction.